Lifted Q2
With the lamp connected directly across speaker terminals I get 13.4 volts on both positive and negative speaker terminals .
If I measure directly across speaker terminals with lamp connected or disconnected I get 0.00 volts .
The lamp did not light up
With the lamp connected directly across speaker terminals I get 13.4 volts on both positive and negative speaker terminals .
If I measure directly across speaker terminals with lamp connected or disconnected I get 0.00 volts .
The lamp did not light up
U1
Pin 1:0.44
Pin 7:.48
U3
Pin 1:0.31
Pin 7:0.49
Pic 1: pin 1 of U1
Pic 2: pin 7 of U1
Pic 3: pin 1 of U3
Pic 4: pin 7 of U3
Scope set to 5 us .5 volts div
Pin 1:0.44
Pin 7:.48
U3
Pin 1:0.31
Pin 7:0.49
Pic 1: pin 1 of U1
Pic 2: pin 7 of U1
Pic 3: pin 1 of U3
Pic 4: pin 7 of U3
Scope set to 5 us .5 volts div
Attachments
I think U1 may be defective. I'm not absolutely certain about this but it's a common IC so you should have it in stock.
See post above .
Also do you happen to know the value of R14 ?
It’s discolored and measures 40k ohms wondering if that’s the correct value or if it’s out of tolorance
Also do you happen to know the value of R14 ?
It’s discolored and measures 40k ohms wondering if that’s the correct value or if it’s out of tolorance
R14 is 39k.
Do you have any other Stetsom (or other Brazilian) amps that use this configuration at this point in the circuit?
What does the output of U1 look like? Still the same?
Do you have any other Stetsom (or other Brazilian) amps that use this configuration at this point in the circuit?
What does the output of U1 look like? Still the same?
Output still looks the same
And I do t have any other Brazilian amps here that use the configuration right now
And I do t have any other Brazilian amps here that use the configuration right now
Remove U1.
Drive a 100k 1v sine wave into the point where R19 and R20 connect.
What do you see on pin 1 of U3?
Drive a 100k 1v sine wave into the point where R19 and R20 connect.
What do you see on pin 1 of U3?